Handheld Sudoku (Assuming You Have Large Hands)

[Hari Waguna] wanted to build a computerized Sudoku game. Ordinarily, that wouldn’t be a big deal. You can buy one, of course, but what fun is that? There’s plenty of apps for phones, but again, not much of a challenge. If you want to preserve your hacker cred, you’d use a CPU board like an Arduino or a Raspberry Pi with an LCD screen, right? But if you want to grow your hacker cred, you’d follow [Hari’s] lead and use 81 seven-segment displays and a membrane keyboard.

Driving that many displays takes some doing (in this case shift registers). [Hari] uses some other tricks, like reading the keyboard using a single pin (and a resistor network). He’s made several videos about the project, including the one below.

The PCB measures eight inches by a little over five inches. Maybe that’s handheld. Practical? Probably not. Cool? Undeniably.

We’ve seen something similar before, although perhaps not as compact. If you really want street cred, you can always try nixie tubes.

11 thoughts on “Handheld Sudoku (Assuming You Have Large Hands)

  1. Well Lana Kane hands rejoice, I saw a definite Trump hands pocket sudoku the other day, I was messing with it for a few mins wondering if I wanted it to cram a duino in or something, but realised I’d get hand cramps trying to use it, also wouldn’t have been able to get much of a screen on it.

  2. Insert of the keypad, could he light up each digit at time and with a light sensor identify wich display is litten?(Like a sensor pen) I think I saw kind of “touchscreen” led matrixes here before. Maybe is just a fools thought.

  3. With a extra display for the currently selected number, you could use the LED’s as a sensor and not need a keyboard.

    As a person who did the cube as a kid, I was very interested in the math / symmetry of the Sudoku puzzle.

    So here’s the low down –

    Condition: The puzzle has 123456789 across the first row and 234567891 across the second etc.

    This solution can be transformed into every other solution in two ways.

    1) number substitution. 1 becomes 5, 5 becomes 7 and 7 becomes 1 etc.
    2) Symmetrical transposition where the transposition can be across the middle of three cells or a transposition of groups of three cells across the middle either horizontally or vertically and even diagonally but diagonally is just a summation of a mix of vertical and horizontal.

    This means that every unsolved puzzle is essentially identical with all the others of the same difficulty.

    It also mean that there is by far not as many different permutations as some claim.

    1. There are some details about the schematic in the video titled “Mega Sudoku Giant PCB”.

      It’s basically 9 rows of 9 7-segement displays with one 8-bit 74HC595 shift register for each row to contain the segment information for the column that is currently selected my the uC. There is probably some power drive to assist the uC as a GPIO will not likely drive that many displays directly.

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